In general, there are T.V. programs for which the viewers want to record the broadcast information for future reference. For example, in a "How-To-Cook" program the housewives want to record the cooking information on the T.V. screens. However, under the present system of television receivers they have to write it down in their notebooks while watching the T.V. screen. This is very troublesome, and is actually a difficult task because they must catch up with the constant flow of the images on the screen, which go on without considering the viewers' convenience. Recently, videotape recorders have been developed, and it is true that they have solved this problem to a great extent. However, in reproducing the videotape it is neccesary to search and select that part of the tape in which the information wanted by the viewer is recorded. As generally known, the re-playing of selected parts of the tape is time- and labor-consuming, so that housewives are often discouraged from reproducing the videotape in spite of the toil paid by them in recording.
In order to solve the inconvenience mentioned above, the inventor has made an invention which provides a printer for automatically hard-copying the pictures on the T.V. screen by writing the gradation density signals of the T.V. pictures in the RAM at real time, and reading them out.
In addition to the picture broadcasting, it is recently desired that characters also be broadcast on T.V. According to this new type of broadcasting, weather forecasts and news reports are broadcast in characters alone or together with pictures on a CRT tube. In this character broadcasting the transmission of character data is performed by inserting the character data in digital form within the period of time for the vertical blanking of T.V. signals, and at the receiver side the character data is temporarily stored in the memory of a character decoder, in which the data is converted into such signals as to be capable of visual display on the screen of a CRT.
In order to print out the character information by the printer invented by the same inventor, it is necessary to read the character data from the memory in the character decoder by the CPU in the decoder, and to print it out by the printer.
However, the memory in the character decoder has a limitation in its storing ability, that is, the content of the memory is automatically replaced by the next-transmitted data. As a result, to effect the print-out of the character data with the use of the memory in the character decoder and the CPU in the afore-mentioned, manner, the data transmitting speed must slow down considerably so as to allow the printing speed to keep pace therewith. If the next data is written in the memory before the transmission of the former data is finished, it is impossible to print out the characters in a clean, normal manner. To remedy this, it will be necessary not to start the writing of the data until the data to be printed out is completely transmitted. This results in the discontinuity of the pictures.